Children's Hospital Los Angeles, University of Southern California Keck School of Medicine , Los Angeles, CA , USA.
Front Pediatr. 2014 Dec 3;2:134. doi: 10.3389/fped.2014.00134. eCollection 2014.
Clinicians are often concerned that higher positive end-expiratory pressure (PEEP) will decrease cardiac index (CI). PEEP affects CI through multiple inter-related mechanisms. The adult Rhesus monkey is an excellent model to study cardiopulmonary interaction due to similar pulmonary and chest wall compliances to human infants.
Our goal was to examine the impact of increasing PEEP on CI in Rhesus monkeys as a model for critically ill children.
Prospective, experimental animal study. Nine healthy anesthetized, intubated Rhesus monkeys were allowed to breathe spontaneously at a PEEP of 0, 5, 10, and 15 cm H2O while CI was measured with an ultrasonic Doppler (USCOM).
Cardiac index decreased between PEEP levels of 5 and 15 cm H2O. The mean decrease in CI for the entire cohort of monkeys was 18% (p < 0.01) with a range of -11 to 49%. Stroke volume and oxygen delivery also decreased between PEEP levels of 5 and 15 cm H2O (p < 0.01).
Between PEEP levels of 5 and 15 cm H2O, there was a decrease in CI, stroke volume, and oxygen delivery in intubated Rhesus monkeys. A plausible mechanism is that over-distention of normally compliant lungs at increased PEEP resulted in decreased preload to the right ventricle, outweighing the potentially beneficial decrease in left ventricular afterload or pulmonary vascular resistance. Further investigation is warranted, particularly in children with lung injury, who have historically benefited from increased PEEP levels without over-distention.
临床医生通常担心较高的呼气末正压（PEEP）会降低心指数（CI）。PEEP 通过多种相互关联的机制影响 CI。恒河猴是研究心肺相互作用的理想模型，因为其肺和胸壁顺应性与人类婴儿相似。
我们的目标是研究在恒河猴模型中增加 PEEP 对 CI 的影响，该模型可用于研究危重病儿童。
前瞻性实验动物研究。9 只健康麻醉、插管的恒河猴在 PEEP 为 0、5、10 和 15 cm H2O 时自主呼吸，同时使用超声多普勒（USCOM）测量 CI。
在 PEEP 水平为 5 和 15 cm H2O 之间，CI 降低。整个猴群的平均 CI 下降 18%（p<0.01），范围为-11%至 49%。在 PEEP 水平为 5 和 15 cm H2O 之间，每搏量和氧输送也降低（p<0.01）。
在 PEEP 水平为 5 和 15 cm H2O 之间，插管恒河猴的 CI、每搏量和氧输送均降低。一种合理的机制是，在较高的 PEEP 下，正常顺应性的肺过度膨胀导致右心室前负荷降低，超过了左心室后负荷或肺血管阻力降低的潜在益处。需要进一步研究，特别是在肺损伤的儿童中，他们从增加 PEEP 水平而不发生过度膨胀中获益。
